A cyclic olefin resin has a backbone of cyclic olefin as a main chain. It is a resin having many characteristics such as high transparency, low birefringence, high heat deformation temperature, lightweightness, dimensional stability, low water absorptivity, hydrolysis resistance, chemical resistance, low dielectric constant, low dielectric loss and being free of environmentally hazardous substances. For this reason, a cyclic olefin resin is used for a wide variety of fields in which these characteristics are required.
Although a cyclic olefin resin has many superior characteristics as described above, physical properties thereof may need to be improved in certain cases. One of the issues required to be improved is to satisfy both transparency and impact resistance. Improved methods are disclosed in which for an injection molded article and a press molded test piece intended for use in containers, a cyclic olefin resin is used together with a styrene based elastomer, and the difference in the refractive index is adjusted (see Patent Documents 1 and 2).
Patent Document 1: Japanese Unexamined Patent Application, Publication No. H10-95881
Patent Document 2: Japanese Unexamined Patent Application, Publication No. H11-21413